In conventional washing machines, the washing action is achieved by oscillation of an agitator disposed within a washing machine basket which contains the clothing items to be washed and fluid for washing the clothes. After each wash and rinse agitation step in the cycle, the liquid is extracted by a high speed rotation of the basket. Current washing machine designs thus require a transmission mechanism for establishing alternate drive to the washing machine agitator or the clothes receiving basket.
U.S. Pat. Nos. 2,751,773; 2,844,225 and 2,946,409 each disclose washing machine transmissions which offer the advantage of a simple actuation of the transmission by reversal of the drive motor, such that in a first direction of rotation of the drive motor an oscillation mechanism is actuated which is coupled to an agitator drive shaft. The oscillation mechanism is carried on a gear frame secured to a spin tube connected to the washing machine basket. The gear frame is braked to the stationary housing during the drive of the oscillation mechanism to produce the agitator oscillation.
Upon reversal of the direction of the input from the motor, the gear frame is clutched to the input drive of the transmission, the brake is released, and the entire assembly rotates to produce basket spin.
While offering the advantage of a relatively simple transmission structure, with no controls required since the simple reversal of the drive motor carries out the change in drive mode between agitation and spin, the arrangement requires a relatively massive gear frame together with all of the components of the oscillation mechanism to rotate at relatively high speed during the basket spin drive mode.
This has the disadvantage of requiring relatively large clearance spaces between the transmission housing and the gear frame, increasing the volume occupied by the transmission housing and also requiring a relatively large volume of transmission lubricant to occupy the interior space.
Also, the relatively large mass of the gear frame rotated at high speed increases the potential unbalanced forces generated during spin.
Other transmission designs, while not requiring rotation of a gear frame and oscillation mechanism, have generally been of relatively complex configuration or require shift controls.
In current washing machine designs, there is often provided a drain-down interval in which the water within the basket, and the tub in which the basket is mounted, is pumped down prior to the initiation of the basket spin. Since only a single drive motor is provided to drive the drain pump and the transmission, delay means are provided for delaying the initiation of the basket spin or rotation some predetermined interval after the drive motor is energized for rotation in the direction resulting in basket spin. The pump is operated, in response to rotation of the motor in this direction, to drain liquid from the basket and tub. Thus a substantial part of the liquid is drained before basket rotation begins.
Such delay means can be provided by an electrical control over a clutch interposed between the electric motor and the transmission or by a mechanical delay which may be built into the clutching unit by way of example.
It would be advantageous to provide the delay by the washing machine transmission itself. That is to provide a neutral in the washing machine transmission, such as to conveniently allow the introduction of a delay period after the initiation of motor operation for spin drive.
Accordingly, it is an object of the present invention to provide a transmission for producing an oscillatory and rotative drive for connection to the washing machine agitator and basket, respectively, which causes an alternate drive upon reversing direction of input drive from the drive motor in which large mass rotating components are not required and which may be contained within a relatively compact housing structure.
It is a further object of the present invention to provide such a transmission which does not involve a complex configuration or the necessity for separate actuation controls, in which the drive therethrough automatically shifts from the oscillating agitator drive mode to the basket spin mode upon a simple reversal in direction of the rotary input drive.
It is still a further object of the present invention to provide such a washing machine transmission which is provided with a neutral condition in the spin drive mode to enable the incorporation of a time delay in the initiation of the basket spin drive after the input drive is established in the direction tending to produce basket spin rotation.
It is yet another object of the present invention to provide such a washing machine transmission which is relatively simple in configuration, incorporating components which are reliable in operation and rugged in construction to enable the transmission to be manufactured at relatively low cost while being reliable in operation.